Evidence that Spt4, Spt5, and Spt6 control transcription elongation by RNA polymerase II in Saccharomyces cerevisiae.
Previous characterization of the Saccharomyces cerevisiae Spt4, Spt5, and Spt6 proteins suggested that these proteins act as transcription factors that modify chromatin structure. In this work, we report new genetic and biochemical studies of Spt4, Spt5, and Spt6 that reveal a role for these factors in transcription elongation. We have isolated conditional mutations in SPT5 that can be suppressed in an allele-specific manner by mutations in the two largest subunits of RNA polymerase II (Pol II). Strikingly, one of these RNA Pol II mutants is defective for transcription elongation and the others cause phenotypes consistent with an elongation defect. In addition, we show that spt4, spt5, and spt6 mutants themselves have phenotypes suggesting defects in transcription elongation in vivo. Consistent with these findings, we show that Spt5 is physically associated with RNA Pol II in vivo, and have identified a region of sequence similarity between Spt5 and NusG, an Escherichia coli transcription elongation factor that binds directly to RNA polymerase. Finally, we show that Spt4 and Spt5 are tightly associated in a complex that does not contain Spt6. These results, taken together with the biochemical identification of a human Spt4-Spt5 complex as a transcription elongation factor (Wada et al. 1998), provide strong evidence that these factors are important for transcription elongation in vivo.
Hartzog
G A
GA
Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Wada
T
T
Handa
H
H
Winston
F
F
D000595:Amino Acid Sequence; D002868:Chromosomal Proteins, Non-Histone; D003080:Cold Temperature; D005656:Fungal Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D005800:Genes, Fungal / Q000235:genetics / Q000502:physiology; D016153:Genes, Suppressor / Q000235:genetics; D056488:Histone Chaperones; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D011485:Protein Binding; D012319:RNA Polymerase II / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D035165:Transcription Factors, General; D014158:Transcription, Genetic / Q000235:genetics / Q000502:physiology*; D035602:Transcriptional Elongation Factors
D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins; D056488:Histone Chaperones; D009687:Nuclear Proteins; C080991:SPT4 protein, S cerevisiae; C065456:SPT6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D035165:Transcription Factors, General; D035602:Transcriptional Elongation Factors; C018648:transcription factor S-II; C069940:SPT5 transcriptional elongation factor; D012319:RNA Polymerase II